Staggered-segment arch



Sept. 10, 1935. w. E. WILSON STAGGERED SEGMENT ARCH Filed July 31, 1935 2 Sheets-Sheet l Sept. 10, 1935, w. E. WlLS ON STAGGERED SEGMENT ARCH 2 Sheets-Sheet 2 Filed July 31, 1933 Patented Sept. 10, 1935 F IE Claims.

This invention relates to improvements in staggered-segment arches; and it comprises in arch structures having a plurality of arch-rows of wooden or metal arch segments arranged in end 5 to end relation, the joints between the segments of one row overlapping the joints in adjacent rows, the improvements comprising means, advantageously in most cases sections of structural iron clamped over the joint between the ends of 1 segments and also attached to the central portions of segments in an adjacent row, holding the ends of the segments in end to end relation, and adapted to enclose or clamp the ends of wooden segments when such are used, preventing splitting; and it further comprises a spaced arch rib wherein each arch segment is made of two component arch rib segments, and web spacing means holding the two segments in spaced vertical relation; all as more fully hereinafter set forth and as claimed.

In the patent to Wilson No. 1,654,625 on which the present invention is, in some of its aspects, an improvement, there is described a form of arch construction which comprises two or more 251 arches or ribs side by side and in contact, each composed of a plurality of separate similar thrustsupporting members or segments, ordinarily of the same length, arranged end to end, with the joints of one arch overlapping those of the other arch, each segment carrying at its middle means adapted to hold the abutting ends of adjacent segments in end to end relation. This form of arch construction has been found highly convenient and economical.

Wood is an ideal structural material for many purposes. It is light and strong. It is comparatively cheap, and is often available from nearby sources. Properly cared for it is permanent. Certain precautions must, however, be taken in using wood structurally. The thrust must be mainly along the fibers; in the direction of the grain. This is especially true in heavy construction, Shearing forces must be-avoided. Accordingly, in heavy construction the wood is generally used as straight members taking the stress directly along their length. Long unbraced spans are avoided. Wood truss bridges or trestles are made of straight members, with no one of them taking. any great lateral strain unsupported.

When used for curved construction, e. g. wagon wheels, the condition that the stress be along the grain, necessitates bending the wood; a diflicult operation; or else using short straight-grained sections; in which construction the joint pres- 5 ents difl'iculties. Another requirement in construction with wood is to keep the wood from .splitting, especially at the ends or joints. If

these two requirements be met, wood construction will be strong and reliable.

In the acknowledged patent there is disclosed 5 the use of wood in a heretofore unexploited construction; in arches. This object is. attained by using arch segments of unbent wood, so short in comparison to the length of the arch that the stress is almost entirely along the grain of the 10 wood. By using two or more rows of overlapping segments side by side, there is provided a much stronger jointed structure than if a single row of segments, joined merely with butt joints, were used. Further means are provided for keeping 15 the ends of the segments from splitting, the means comprising enclosing sleeves for the joints.

This patented form of arch construction is equally applicable to metal. Short ready-cut lengths, either straight or curved, can be used. The costly operation of bending long pieces is avoided. In each case, besides the stated advantages, there is the additional advantage that labor in assembling an arch rib from the component segments is reduced to a minimum, as the 5 segments are all made alike, and each may be provided with couplings so that the main labor required in setting up the arch is that of lifting the segments into position.

The present invention in one of its embodiments 0 relates to improvements in coupling and joint bracing means for the segments, enabling the completed arch to withstand extremely great loads, especially if it is made of steel. These means comprise in general short sections of 35 channel or angle iron disposed so as to strengthen the joints, and adapted to prevent splitting of wooden segments when such are used.

In an arch structure having overlapping segments the lateral stiffness and strength are not so 40 great as they would be in a theoretical unitary structure of equivalent form. This is especially true when the arch is composed of but two rows of segments fastened together. Each joint between segment-ends is in effect a saw-cut part 5 way through the arch rib. I gain increased lateral stiffness in the structure shown in the acknowledged Wilson patent by use of a sleeve at each segment joint. This keeps the ends of the segments in one row from spreading laterally 50 away from the adjacent segment in the adjoining row, upon application of a lateral distorting force. Ample lateral stiffness is provided for all ordinary uses.

Great lateral stiffness is not ordinarily of much importance, as in most arch structures, for instance in bridges and roofs, the arch can be braced at intervals by struts and the like against any lateral stress tending to deform the arch. Thrust in most arch structures is mainly vertical. When the thrust is entirely vertical, a composite arch is fully as strong as a unitary one. Cross braces, roof beams, or the like are ordinarily sufiicient bracing against lateral deformation. Occasionally, however, it is desired to strengthen an arch or truss in itself, against lateral stresses. In order to secure lateral stiffness in an arch rib composed of two rows of segments with the joints of one row overlapping those of the other row, in the present invention I provide at each jointa short joining member, advantageously of iron, bolted through the ends of the two abutting segments and through the middle portion of the segment in the adjacent row. Flat strips may be used but the use of angle or channel irons is advantageous as they give additional stiffness to the joint. The joining members may be, and ordinarily are, used in conjunction with a sleeve. The arch so reinforced is substantially as strong against lateral stresses as a unitary structure. The means disclosed may be supplemented by a cap strip of Wood or metal bolted or nailed along the top of the arch rib, advantageously to the sleeves when such are used. My invention can be applied with equal success to wooden and to metal arch ribs.

In the accompanying drawings I have shown, more or less diagrammatically, several embodiments of my invention. In this showing,

Fig. 1 is a view in elevation of a portion of an arch rib made up of sleeve-carrying segments;

Fig. 2 is a sectional view taken along the line 22 of Fig. 1;

Fig. 3 is a view in elevation of a rib segment made up of three rows of arch segments, the central row having segments heavier and thicker than those in the outside rows, and projecting above those in the outside rows, the figure show ing angle iron joining means;

*Fig. 3A is a sectional view or" a modification of the embodiment shown in Fig. 3;

Fig. 4 is a sectional view taken along the line l4 of Fig. 3;

Fig. 4A is a sectional view taken along the line 4A'3A of Fig. 3;

Fig. 5 is a view in elevation of a portion of a double arch rib, showing a section of channel iron carried at the middle of each segment and enclosing the joint of the abutting ends of adjacent segments;

Fig. 6 is a sectional view taken along line 68 of Fig. 5;

Fig. '7 is a view in elevation of a modification of the design shown in Fig. 5, wherein both edges of the segments are curved. the segments being of constant width, the figure showing channel iron joining means;

Fig. 8 is a sectional view taken along the line 88 of Fig. 7;

Fig. 9 is a View in elevation of a modification of the design shown in Figs. 3 and 4, showing a double arch rib with joining means comprising a bent angle iron;

Fig. 10 is a section along the line Hll!l of Fig. 9;

Fig. 11 is a view in elevation of a modified arch design adapted for very heavy construction;

Fig. 12 is a sectional view taken along the line [2-12 of Fig. 11;

Fig. 13 is a View in perspective of a bearing plate adapted for use with the above designs;

Fig. 14 is a view in elevation of a modification of the design of Fig. 3 using angle iron segments;

Fig. .15 is a sectional view taken along the line 5 |!5i5 of Fig. 14;

Fig. 16 is a sectional view of a modification of the design of Fig. 14, using channel iron segments;

Fig. 17 is a view in elevation of an arch rib 10 cc-mprising overlapping double segments, each double segment comprising two single segments and web spacing means; and

Fig. 18 is a sectional view along the line i8i8 of Fig. 17,. 15

Referring now to the drawings in which like reference numerals indicate like parts,

Figs. 1 and 2 show a portion of an arch rib, made up of two rows, side by side, of wooden arch segments i, each segment carrying at its middle a 20 sleeve adapted to hold the ends of the adjacent segments in end to end relation. The sleeve is suitably reinforced by a short section of angle iron 3, held by the bolt in the manner shown. This construction allows of the sleeve being made a of very thin material or even sheet metal, by providing maximum support only at the required area. The sleeve need be only strong enough to hold the two rows of arch segments together. Saving in material and weight is obtained. If :11, desired, a cap piece of wood or metal may be bolted along the top of the rib, advantageously to the sleeves.

Figs. 3, 4 and 4A show a modified form of construction wherein the sleeve is omitted. The 35.1 form illustrated is a triple arch, rather than a double arch. The central row is composed of segments 4 heavier than those in the outer row and projecting above the other segments in the manner shown to provide a shelf for the ends 493 of rafters or the like which may rest upon the rib. Two pieces ofangle iron 5 are bolted to the center of each central segment, and the ends of adjacent segments are bolted to the angle irons with vertical bolts in the manner shown. At the alternate joints, where the central rib joints are inside the outer segments, a channel iron joining member 1 is used, as shown. This form of construction presents many advantages over mere bolting or nailing the segments together. 501: The ends of the outer segments are not weakened by transverse bolt holes; there is only one transverse bolt hole and it is through the thickest part of the heavy central segment. The vertical q bolts 8 hold the ends of the outside segments securely in place, and as there is little or no twisting strain on the arch rib, there is no force that would tend to split the wood around the bolt holes. The type of construction shown in 60, Figs. 3 and 4 can equally well be adapted for use with a double arch, as shown in Figs. 9 and 10. The same advantages are found. As shown in Figs. 9 and 10, the angle iron may be bent to the angle included by the under side of adjoining segments, the segments not being notched in this case.

The central projecting rib, as shown in Fig. 3 may project farther above the outer ribs than is shown in Fig. 3, and flanged metal members, such as sections of angle iron, may be attached to the projecting portions at positions above the joints between the ends of the segments in the outer rows, and engaging the segment ends. Such supporting members, which support the T-iro-ns rather than angle irons.

outer segments from above, may be used in conjunction with a lower support of the type shown in Figs. 3 and 9 for example. An embodiment making use of supporting members both above and below the segment joints is shown in section in Fig. 3A. In this figure the arch rib is made of two adjacent rows of arch segments, as shown. Flanged supporting members 6 are placed above and below the joint. The upper supporting members may be used alone, the lower supporting members being omitted. Both upper and lower supporting members may take the form of continuous strips of metal, running the length of the arch rib, the upper members being attached to the projecting sides of the projecting segments, the lower members to the under sides of the arch segments.

Figs. 5 and 6 show a modified form of construction wherein the ends of the arch segments are held against dislocation, and the joint braced, by a section of channel iron 9 bolted over the joint with bolt Hl therein. Again, as in Figs. 3 and 4, the bolt hole is made through the thickest, central part of the segments. The thinner end-portions are not pierced, but are securely held by enclosing clamping means, any tendency to split being effectively overcome by the enclosing metal channel.

Figs. '7 and 8 show a modified form of the construction shown in Figs. 5 and 6. Here the arch segments are curved along each edge; they are of uniform width. The joint-bracing means is here shown as two sections of channel iron 9, drawn together by bolt I0.

Figs. 14, and 16 show a modification of the construction shown in Figs. 3 and. 4, adapted for use with metal segments. In Figs. 14 and 15, the segments l are curved lengths of angle iron, and each carries at its middle 2. short section of angle iron 6 bolted to the segment and adapted to hold the ends of the adjacent segments. A single bolt sumces, but two may be used, one through the end of each segment. The segments are sometimes advantageously made of Channel irons can be used, in which case angle irons 6 may be replaced by a channel iron section. Fig. 16 is a sectional view of such a modification.

Figs. 17 and 13 show an arch rib comprising overlapping double segments, each double segment comprising two single components I held in spaced vertical relation by web members I4. Each double segment is a unitary structure, and the web members, which may be rods or the like, are advantageously welded to the single segments. The double shelf arrangement at the top forms a highly advantageous support for roof construction, such as rafters, slabs, or the like. In the assembled arch, the double segments and their webs overlap as shown.

Figs. 11, 12 and 13 show a modification of the construction shown in Figs. 3 and 4, adapted for use in heavy structures such as bridges. The segments I are clamped at the ends by angle iron section 6 and bolts H1. The construction is thereby reinforced against lateral stresses. Along the topof the arch rib is nailed or screwed by suitable means, such as screws II, a cap piece 12 which gives even greater lateral stifi'ness as well as strengthening the arch against vertical stresses, and protecting the arch from the elements. Between the abutting ends of the segments are metal plates 13, advantageously, but not necessarily, pronged so as to stay in place. An enlarged view of one of these plates is shown in Fig. 13 in perspective. The use of these plates prevents the ends of the segments from digging into each other because of their grained structure; the plates prevent splitting of the wood.

The use of such plates is advantageous wherever 5 great stresses have to be supported by wooden members.

The various embodiments of my invention show simple and economical means for joining the ends of arch segments. The segments can be 1 0 fitted together with a minimum of labor and expense; in the embodiment shown in Fig. 1 more setting of the segments into position is all that is necessary, each segment being preformed, prefitted and predrilled. In every embodiment us- 15 ing wood, the wood at the segment joints, the most vital part, is protected against splitting; by a sleeve in the design of Fig. 1, vertical belts in Fig. 3, a channeled section in Figs. 5 and '7, and bearing plates and a cap piece in Fig. 11. A 20 much stronger construction than mere bolting or nailing the segments to each other is obtained. Tendency of the wood to split, especially at the ends, is minimized. In each case the abutting, segment ends are supported against vertical displacement, the joining means engaging a horizontal face, that is the top or bottom, of the segment ends, and giving positive vertical support.

In the embodiments using metal segments, reinforcement is provided at the proper points, with a minimum of drill holes. The construction shown in Figs. 1, 5 and 14, wherein only one bolt is used, presents many advantages. Only one hole need be drilled in each segment. Each segment can be sent to the user carrying the channel iron or angle iron section loosely bolted to it, thus only fitting the segments into place and tightening the bolts is necessary, the troublesome operations of centering, reaming, etc. being eliminated. As in the wood embodiments, the coupling means afford vertical as well as horizontal support for abutting segment ends.

By using my invention the structural advantages of wood are utilized to their full extent. 4-5 Strong and permanent wooden arches, suitable for use in large spans such as armory roofs and the like can be constructed cheaply, using a minimum of material. The arch may be a simple circular are, or of any other arch shape. Pointed or gothic-type arches may be made. In addition. the arch may be reinforced locally, by using a greater number of segments laterally. All the embodiments disclosed are adaptable for use in trusses, with slight modifications. By using my invention wood can be utilized in heretofore unheard-of relations.

Similar economies are found in the use of my invention with steel. Heavy bridges and the like can be made that are light but strong, with a great reduction in cost, and in the labor of construction.

The ends of the segments in the embodiments shown in Figs. 1 to 5 are shown as being notched or indented. This notching is advisable when straight metal joining members are used, as in Figs. 1 to 5, but can be dispensed with when the joining member is made to follow the angle between the lines of the segments, as shown in Figs. '1, 8, 10 and 14, or is mounted upon the perpendicular face of the segments, as in Fig. 11. In the showings the curvature of the arch ribs is exaggerated for the sake of clarity of presentation. Ordinarily arch ribs are made of flatter curvature, and the depth of notching is not great.

What I claim is:

1. In an arch rib having a plurality of adjacent rows of arch segments, coupling means supporting the segment ends horizontally and vertically and comprising a member of flanged metal attached to the middle part of each segment in one row and engaging a horizontal face of the end portions of the abutting segments in adjacent rows and means fastening the ends of the abutting segments to the flanged metal member so that the ends of the abutting segments are supported horizontally and vertically.

2. In an arch rib having a. plurality of adjacent rows of arch segments, coupling means supporting the segment ends horizontally and vertically and comprising a member of flanged metal attached to the middle part of each segment in one row and engaging the bottom face of the end portions of the abutting segments in adjacent rows and means fastening the ends of the abutting segments to the flanged metal member, so that the end portions are supported from below and vertical displacement thereof with respect to each other is prevented.

3. In an arch rib having a plurality of adjacent rows of arch segments, the segments in some rows projecting above the segments of other rows, means attached to the projecting portion of the segments in the projecting rows, engaging the top of, and supporting, the segments in the other rows.

4. In an arch rib having a plurality of adjacent 'rows of arch segments, the segments in some rows projecting above the segments of other rows, a plurality of metal members attached to the projecting portion of the segments in the projecting rows, and supporting the ends of the segments in the other rows, at the segment joints.

5. In an arch rib having a plurality of adjacent rows of arch segments, coupling means comprising a member of metal attached to the middle part of each segment in one row, and engaging !and supporting from above, the ends of the abut- ,ting segments in adjacent rows, said member also engaging and supporting laterally the side portions of said abutting segment ends.

6. In an arch rib having a plurality of adjacent ,rows of arch segments, coupling means comprising a member of metal attached to the middle 11 part of each segment in one row, and adapted to support, from above, the ends of the abutting segments in adjacent rows, and means fastening the ends of the abutting segments to the metal member. 10

'7. In an arch rib having a plurality of adjacent rows of arch segments, coupling means comprising a plurality of members of metal attached to the middle part of each segment in one row, and

adapted to support, from above and from below, 15'

the ends of the abutting segments of adjacent rows.

8. In an arch rib having a plurality of adjacent rows of arch segments, coupling means comprising a plurality of members of metal attached to 20 the middle part of each segment in one row, and adapted to support, from above and from below, the ends of the abutting segments of adjacent rows, and means fastening the ends of the abutting segments to the metal members.

9. An arch rib comprising a plurality of adjacent rows of arch segments and coupling means for the ends of the segments, the coupling means being adapted to support the segment ends vertically and horizontally, the segments in one row projecting above the segments in other rows, forming a shelf extending along the length of one side of the arch rib and adapted to receive ends of the rafters.

10. An arch rib comprising two adjacent rows of arch segments, and coupling means for the ends of the segments, the coupling means being adapted to support the segment ends vertically and horizontally, the segments in one row pro- 4 jecting above the segments in the other row, forming a shelf extending along the length of one side of the arch rib and adapted to receive ends of the rafters.

WINFRED E. WILSON. 

